1. Field of the Invention
The present invention relates to an air cleaner, and more particularly, to an air cleaner for an engine of a vehicle that is used at dusty places.
2. Description of Related Art
Concerning the configuration of an air cleaner and a filter element used therein, there have been conventionally known, for example, a double-elements type air cleaner as disclosed in Japanese Unexamined Utility Model Application No. S59-133762, on pages 6 to 7, FIG. 2, FIG. 3 and others (hereinafter referred to as document 1), and a serial type air cleaner as disclosed in Japanese Unexamined Patent Application No. 2000-508974, on page 12, FIG. 1 and others (hereinafter referred to as document 2).
FIG. 14 shows a cross-sectional view of a double-cylinder type air cleaner 70 disclosed in the document 1. As shown in FIG. 14, a cylinder-shaped casing 71 has an inlet pipe 72 formed on the side thereof, and an outlet pipe 73 formed on the center of a closer plate, and a bridge 74 having a couple of leg portions whose ends are welded to the inner side of the outlet pipe 73 extends toward the opened end of the casing 71 with its top portion fixed to a stud bolt 75. At the opened end of the casing 71, there is detachably mounted a dust pan 76. Inside the casing 71, there are arranged a first filter element 80 located adjacent to the casing inner wall and a second filter element 81 located inside the first filter element 80, configuring double-cylinder type.
FIG. 15 shows a perspective view of the first filter element 80. As shown in FIG. 15, the first filter element 80 has a filter 83 that is made of a filter paper or non-woven fabric and is pleated to be formed into a cylinder arranged around an inner cylinder 82 having multiple holes, and an outer cylinder 84 having multiple holes arranged around the filter 83. The first filter element 80 has arranged on the top and bottom thereof an annular end plate 85 provided with an opening at the center thereof, and a closing end plate 86 provided with an opening at the center thereof through which the stud bolt 75 passes, which are fixed using adhesion bond.
The second filter element 81 and the first filter element 80 are inserted into the casing 71 in this order from the dust pan 76 side, and their respective closing end plates 86, 87 are fixed to the stud bolt 75 using screws.
Ambient air taken in from the inlet pipe 72 comes in from the outer circumference side of the first filter element 80, and filtered air is sent to the inner circumference side of the first filter element 80 to pass through the second filter element 81 to be supplied to an engine from the outlet pipe 73. The first filter element 80 is detached to be cleaned when clogging takes place. The second filter element 81 prevents foreign matters from breaking into an engine when the first filter element 80 is detached for cleaning.
FIG. 16 shows a perspective view of a serial type air cleaner 90 disclosed in the document 2. As shown in FIG. 16, between a first facing sheet 91 and a second facing sheet 92, there is arranged a grooved sheet 93 that has mountain portions 94 and valley portions 95 alternately formed thereon. The valley portions 95 and mountain portions 94 form upper grooves and lower grooves, and the downstream end of upper groove rooms 96 is closed by a second end bead 99, while the upstream end of lower groove rooms 97 is closed by a first end bead 98. The central grooved sheet 93 is a filter member.
Unfiltered fluid inflows to upper groove rooms 96 that have their upstream end opened, as shown by black arrows, and is blocked by the second end bead 99. Accordingly, the fluid inflows to the lower groove rooms 97 through the grooved sheet 93, as shown by white arrows, when the unfiltered fluid is filtered. Thus filtered fluid outflows from the downstream end since the upstream end of the lower groove rooms 97 is closed.
However, there is raised the following problem in the configuration disclosed in the document 1.
That is, since both end surfaces of the cylindrical filter elements on the longitudinal direction are closed, the air comes to pass from the outer circumference side to the inner circumference side of the elements, which makes it difficult to sufficiently secure the air-passing area. As a result, pressure loss at the time of taking in air is prone to be large, and there may be raised performance deterioration when used for an engine to take in air. Furthermore, clogging frequently takes place in the elements, which raised a problem that the element cleaning interval is shortened.
On the other hand, as for the configuration disclosed in the document 2, since the direction of air flow accords with the axis direction of elements (direction along the groove rooms 97), the configuration is not appropriate when used for a construction machine that works at dusty places, in which case it is desired that air be taken from the upper side of a machine and be discharged horizontally.